Texas - Formula 1 Race Director Charlie Whiting bowed to drivers' pressure on Saturday when he confirmed a clampdown on the controversial "aggressive defensive" driving used by Max Verstappen.
Whiting had vowed to take action following a heated discussion during Friday night's pre-race drivers' briefing meeting at the Circuit of the Americas ahead of this weekend's United States Grand Prix.
In a revision of the rules as issued to the teams on Saturday, Whiting made it clear that the kind of tactics used by the Dutch teenager in Japan would not be allowed.
Verstappen had changed direction under braking during a battle with defending world champion Lewis Hamilton of Mercedes, forcing the Briton to run off-track and down an escape road.
That penultimate lap scrap was not the first involving the forceful Verstappen whose honeymoon as a young driver in a top team now appears to be over.